Electrical protective device.



H W. BROWN.

ELECTRICAL PROTECTIVE DEVICE.

APPLICATION FILED MAR. 13, I914.

Patented Dec. 3, 1918 2 SHEETS-SHEET 1.

{Jay 4.

AI IIIRNI'Y H. W. BROWN.

ELECTRICAL PROTECTIVE DEVTCE.

APPLICATTGN FILED MAR. TE. 1914.

1,286,2 1s iutvntwl Dru. 5L 19M.

2 SHEETS EH'L'LT 2T 1/ m l wmm I H m WITNESSES: TNVENTUR UNITED STATESPATENT OFFICE.

HAROLD 'W. BROWN, HHACA, NEW YORK, ASSIGNOR TO WESTINGHOUSE ELECTRIC ANDMANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

ELECTRICAL PROTECTIVE DEVICE.

Specification of Letters Patent.

Patented Dec. 3, 1918.

Application filed March 18, 1914. Serial No. 825,448. 1

To all whom it may concern:

Be it known that I, HAROLD BROWN, a citizen of the United States, and aresident of Ithaca, in the county of Tompkins and State of New York,have invented a new and useful Improvement in Electrical ProtectiveDevices of which the following is a specification.

My invention relates to electric motors and particularly to the use ofthe same as protective relays.

The object of my invention is to provide a relay of the motor type whichhas a large range of speed control, thus allowing either a definite, oran inverse, time limit'in its operation.

Heretofore, motor type relays have been provided that embodied adefinite and an inverse time limit in their operation, but the definitetime limit feature was only effective over a very limited range. Toobviate the hereinbefore mentioned disadvantage, I rovide .my invention.as hereinafter descri ed.

Figure 1 of the accompanying drawings is a diagrammatic view, mainly inelevation, of a relay embodying my invention, Fig. 2 is a diagrammaticview, partially in elevation and partially in section of a modi tiedform of a relay embodying my inven tion, Fig. 3 is a view partially inplan and partially in section of a portion of the relay shown 111 Fig.2, and Fig. 4 is a diagram showing the relative torque'curves'obtainable with my invention.

Referrin to Fig. 1 of the drawings, a relay 1 cnnodying. my inventionserves to control the operation of a circuit interrupter 3 that isutilized to open a circuit 2 when overloaded. The circuit interrupter 3is tripped by an electromagnet 4, the winding 5' of which is connectedin series relation to a battery 6 and a switch 7. The relay 1 comprisesa magnetizable core 8 having polar projections 8 and 8 a main winding 9that is connected in circuit with the secondary winding 10 ofatransformer 11, the primary wining 12 oi which is connected in serieswith one conductor of the circuit 2. one or more auxiliary windings 13,adjustable auxiliary pole pieces 15 that project laterally from the mampole pieces the-armature, but it will be understood that upon a shaft 17that also carries a pinion .the switch 7, thus completing a circuit orpolar projections and a rotatable armature member 16.

I have shown each of the pole pieces 8 and 8 between which the armaturlti projects and operates as divided to foriimtwo polar projections ofunequal size, the smalleF.- of which is surrounded by an auxiliaryclosed-circuit winding 13, and I have also shown each main pole piece asprovided with two oppositely disposed laterally projectin pole pieces 15that are so mounted as to he adjustable toward and away from thestructure ma be variously modified, as regards the numlier and characterof polar projections, laterally projecting ole pieces and auxiliarycoils. It will urther be understood that, for certainoperatingconditions, a single polar extension on each side of thearmature may suiiice and also that, in some cases, both auxiliary coilsmay be, omitted. The armature 16 1s mounted 18 which engages a gearWheel 19 thatis mounted upon a shaft 20 upon which the movable member 21of the switch 7 is also mounted. The inner end of a spring 22 isattached to the shaft 17 and its outer end is attached to a stationarymember 23.

lVhen a predetermined overload occurs upon the circuit 2. my inventionoperates as follows:

Sutficient current flows through the windnjiig 9 to cause the windings13 to become e ective and a shifting field is set up that causes thearmatures 16 to turn the shaft 17, the pinion 18 and the gear wheel 19to close through the winding 5 of the electroma et 4 to trip the circuitinterrupter 3. By p acing the auxiliary pole pieces 15 in such positionsas to cause them severally to become saturated to any desired degreewhen an excessive current flows through the winding 9, the resultinredistribution of the magnetic flux and ed y currents in the armaturewill cause the same --to have a resulting speed which will beessentially the same at a large overload as at smaller overloads.However, the members 15 may be so arranged as to pro'vide asubstantiallyinverse time element for the rotating armature 16 of the relay 1.

When the overload on the circuit 2 is relieved, the spring 22, which hasbeen placed under tension, causes the shaft 17 and the armature 16 torotate backwardly to their initial positions, thus opening the switch 7,in a manner that is familiar to those versed in the art.

It will be understood that the projection 15 on the pole portion 8 is soplaced that it saturates when a relatively large current traverses thecoil 9 and the other projection 15 that is mounted adjacent the winding13 is so located that it does not saturate. Thus, the difi'erentialefiect causes the resultant torque to be less than if the iron of thecore was not separated. In other words, the resultant torque may bestated in a formula tobe A-'B whereA is the eflect of the projections onthe portions 8 and the effect of the portions 8 and 8" and B is theeffect of the projections 15 on the other portions of the core.Referring now particularly to Figs. 2 and of the drawings, nil/device,as here shown,

-comprises a relay 1 having a main winding 9, auxiliary windings 13,laterally project: ing pole pieces 15, substantially as shown in Fig. 1and susceptible of modifications as set forth in the description of whatis shown in that figurc, a shaft 24, an armature mem' ber 25 mountedupon the same, a sleeve 26 loosely mounted upon the shaft 24, anarmature member 27 mounted upon the said sleeve, a'spring 28 having itsinner end attached to the sleeve 26 and its outer end to a stationarymember 29, and a lever member 30. The lever member 30 is pivotallymounted upon a stationary member at a point 31 intermediate its ends.*The lever- 30 controls the movable member of a switch 33 that isactuated by the relay 1. through a worm screw 34 which is mounted on theshaft 24 and which engages a worm wheel 35-that is in operative relationto the member 32. The inner end of a spring 36 is attached to a shaft 37upon which is mounted the worm Wheel 35 and the member 32, and its outerend is attachedto a stationary member 38, substantially as shown. Aprojection 39 is mounted upon the armature member 27 and the lever 30 isprovided with aprojection 40 near its lower end having a cam face 41 forengaging the projection 39. A second projection 42 upon the lever 30engages a notch 43 in the periphery of the armature member 25, forpurposes hereinafter set forth,

When sullicient current flows through the winding 9, the armature 27.iscaused to rotate by reason of the eddy currents set up therein by thefield adjacent thereto, as is known by those versed in the art. Theprojection 39 is thus moved into engagement with the projection 40 towithdraw the projection 42 from the notch 43 and to throw the worm Wheel35 into engagement with the worm screw 34. lVhcn-the armature 25 is thusreleased, it rotates to drive the shaft 24, worm screw 34, and wormwheel 35 to close the switch 33, and therchy'insure the operation of thecircuit breaker 3.

When the circuit 2 has been relieved from its overload, and the currentin the winding 9 falls below the predetermined value required to rotatethe armatures 25 and 27, the spring 28 rotates the'armature 27 to itsinitial starting position and permits thelever 30 to turn upon its pivotin such manner as to effect engagement of the projection 42 withthenotch 43 in the p riphery of the armature 25 and disengagement of theworm screw 34 from the worm wheel 35. spring 36, which is tensionedduring the closing operationof the switch 33, is thus released to returnmovable contact member 32 to its initial open-circuit position.

Thus. when the overload is removed from a circuit that is protected bythe modification of my invention shown in Figs. 2 and 3 of the drawings.a substantially instantaneous resetting is achieved by reason of thefact that the armatures do not have to retrace their forward motion inresetting the switch 33.

By modifying the positions of the lateral pole pieccs'15, the overloadtorque curves may be modified from a definite time limit to a markedinverse time limit effect,- as shown in Fig; 4 of the drawing. Also, theshape of the torque curve may be modified'so that it is substantiallyflat in one part and steep in.another or so that it has in all. points,nearly the same slope, according to the cfl'ect desired. Thus the timerequired to trip the circuit breaker 3 may be definite, inverse, orinverse up to a predetermined value of current and definite for 'allvalues of current above the predetermined value.

The windings 13, althoughshown as closed circuit windings with nooutsidcconnection, may be connected in parallel relation tothe circuit 2 if itis esired to operate the relay at a certain wattage instead of a certaincurrent overload. The winding 9 is so proportioned that it will cause asufiicient field to be set up in proximity to the armatures only at apredetermined overload, so that the armatures will not creep on smalleroverloads. The pole pieces 15 may be arranged so that those on one sideof; the core memher 8 may become saturated at certain overloads, and theothers remainjnnsaturated, or they may all be arranged to becomesaturated at predetermined overloads, thus insuring a relatively largeflexible adjustment. The ratio of the gearing may be such that anindefinitely long time limit may be secured.

While I have described my invention in its preferred forms, I desire itto be understood that structural modifications may The made within thespirit or the same Without departing from the scope of the appendedclaims.

I claim as my invention:

1. It. nwtor comprising an armature, a field magnet corehaving a polarprojection adjacent to the armature a main field magnet Winding, anauxiliary Winding surrounding said polar projection, and an auxiliarypole piece projecting laterally from the polar projection adjacent tothe armature, the said auxiliary pole piece being adapted to become sosaturated that the armature will develop a substantially constant torquefor all values of current traversing the main field magnet Winding.

motor comprising an armature, a field magnet core having a plurality ofpolar projections adjacentto the armature, a main field magnet windine',an auxiliary winding upon one of the polar projections of the fieldmagnet core, an auxiliary pole piece projecting laterally from one sideof a polar projection and adapted to become saturated when comparativelylarge amounts of current traverse the main field magnet Winding, andanother auxiliary pole piece that projects la erally from the other sideof a polar projection of the field magnet core and adapted to becomesaturated under predetermined conditions to an amount differing from thesaturation of the first mentioned auxiliary pole. piece.

3. A motor comprising an armature, a field magnet core having a dividedpole piece adjacent to the armature, a main field magnet winding, anauxiliary winding upon one of the polar divisions of the field magt c '1and auxiliary pole pieces projecting tron: opposite sides of the mainrelay comprising an armature, a

\ .izahle core having a main divided pole piece adjacent the armature amain \viiulingz an auxiliary Winding surrounding one of the polardivisions of the magnetizahle core and auxiliary pole pieces projectinglateralv from opposite sides of the main pole pie es. the said auxiliarypole pieces heing adjustable relatively to the armature.

5. A motor eompriving an armature, a field magnet core havii g a polarprojection adjacent to the armature, a main field magnet Winding, anauxiliary closed-circuit Winding surrounding said polar projection, andan auxiliary pole piece projecting laterally from the polar projection.

6. A motor comprising an armature, a field magnet core having a dividedmain pole piece adjacent to the armature, a main field magnet Winding,an auxiliary closedcircuit winding surroundings one of the polardivisions of the field magnet core, and auxiliary pole pieces projectinglaterally from opposite sides of the field magnet, the said auxiliarypole pieces being disposed unequal distances from the armature and oneof them being adapted to become saturated when relatively large amountsof current tra erse the main field magnet Winding.

7. A motor comprising an armature, a field magnet core having a dividedpole piece adjacent to the armature, a main field magnet Winding, anauxiliary elosed-eireuit windingsurrounding one of the polar divi' sionsof the field magnet core, and auxiliary adjustable pole piecesprojecting laterally from the field magnet and adapted to becomesaturatedwhen the current traversing the main field magnet Windingexceeds a predetermined value.

S. A motor comprising an armature, a field magnet core having a divided)ole' piece adjacent to the armature, a main neld magnet winding, anauxiliary closed-circuit winding surrounding one of the polar divisionsof the field magnet core, and an ad justable auxiliary pole pieceprojecting lat orally from the field magnet core and adapt-- ed tobecome saturated when the current traversing the main field magnetWinding ei-cceds a predetermined value.

in testimony whereof, I have hereunto subscribed my name this day ofFeb. 28. 1914v HAROLD VJ. oROiVN.

Witnesses:

5'3. BANKS, .lns; ROBINSON, Jr.

